A horrifying and bizarre mass shooting in Plano, Texas, killed eight people inside a home there Sunday night, WFAA in Dallas reports. One of the dead is the suspected gunman. He was shot and killed by a heroic police officer, who charged into the house on the 1700 block of West Spring Creek Parkway in Plano after hearing shots from inside the home. A group had gathered at the residence to watch a Dallas Cowboys football game on television.

The identities of the other seven slain adults have not been released by police as of early Monday morning, nor have police announced how many of the victims were male and how many were female. Police also say that the motive for the shootings remains unclear in the early hours of September 11, but one witness described an argument between a man and a woman outside the house that appeared to culminate in the man firing multiple shots, according to a KDFW report.

UPDATE 9/11/17, 4:25 p.m. EDT:While police have not yet confirmed the identities of the victims, the mother of Meredith Lane, 27, says that her daughter was killed and that the shooter was her daughter’s ex-husband, according to a WFAA report.

UPDATE: family confirms 27-year old Meredith Lane among 7 killed last night at her Plano home. Mom says ex-husband was shooter, killed by PD pic.twitter.com/KEwRIwTXzO

Meredith Lane owned the home where the shootings took place with her husband of six years, but they had been recently divorced. Collin County property records list the owners of the home as Meredith Hight and Spencer J. Hight, who was 32 years old.

“She was a cook, and a quite fine one, and she loved hosting friends and families,” the victim’s mother, Debbie Lane, told WFAA. “This was her first opportunity to do it after the divorce and he didn’t take it well.”

Also on Monday, police said that an eighth victim, in addition to the gunman, had died as result of wounds suffered in the Texas mass shooting, according to a report by KTSM TV News in El Paso. The death brings the total killed in the shooting to nine.

A witness, Crystal Sugg, who works in a nursing home nearby to where the killings took place, told the station that the man, whom she did not identify, started “releasing” shots when the woman involved in the confrontation attempted to go back inside the home. Sugg said that she then ducked into her own building to seek safety from any possible stray bullets.

Watch Sugg give her eyewitness account of the violent confrontation in the video below.

Crystal Sugg describes the altercation she saw between shooter & a woman before shooting started in Plano. pic.twitter.com/U9yqdkN2Kh

The witness said that the argument took place at around 7:45 p.m. She estimated that between 30 and 40 shots were fired inside the home.

In addition to the seven dead adults and the suspect, two other victims were injured and rushed to a nearby hospital for treatment, according to a report by KTVT in Dallas. Plano is a suburb located to the north of Dallas with a population of about 260,000.

Plano police officers received a call at about 8:05 p.m. reporting a man with a weapon at the home, and when they arrived on the scene they heard gunfire inside the house. The first officer to enter the home immediately spotted and confronted the suspect, and the two exchanged gunfire. The officer’s bullets struck the alleged gunman, killing him, according to the WFAA report.

No police officers were injured in the incident.

“I’ve been here all my life. I’ve never heard of anything like this,” said Plano police spokesperson David Tilley, quoted by the Dallas Morning News.

According to that paper, the couple who are listed in public records as owning the home where the shootings took place were in the process of a divorce. Neighbors said that the shootings stemmed from a domestic dispute, the Dallas MorningNews reported. Police have not confirmed those reports as of early Monday morning.

The identity of the alleged shooter has not been released, and the condition of the hospitalized, surviving victims has also not been made public as of 12:05 a.m. Central Daylight Time. But reporter Allison Harris of KDFW reported that she spoke to four men who had been at the house, but departed prior to the violence. The men told her that the gathering inside the home was a “watch party” for the Dallas Cowboys football game, which was televised on Sunday night.

The organization Mass Shooting Tracker, which defines a “mass shooting” as any shooting with four or more victims in a single incident — including those who survive — reports that Sunday’s Plano, Texas, event was the 311th mass shooting of 2017 in the United States. After 251 days so far in this year, that’s a rate of approximately 1.25 mass shootings every day in 2017, on average.